Patent Application
20230350316
The present invention relates to an electrophotographic photosensitive member, a process cartridge including the electrophotographic photosensitive member, and an electrophotographic apparatus including the electrophotographic photosensitive member.
In recent years, the diversification of the users of an electrophotographic apparatus has been advancing, and hence there has been a growing need for an improvement in quality of an image to be output as compared to a conventional image.
In International Publication No. WO2019/077705, as a technology concerning an improvement in image quality, there is a description of a technology including setting the internal stress value of an electroconductive support within the range of from -30 to 5 MPa.
In Japanese Patent Application Laid-Open No. 2009-150958, as a technology of improving image quality from the viewpoint of accuracy, there is a description of a technology including heating an element tube made of an aluminum alloy at a temperature of from 190 to 550° C. before its cutting.
In addition, in Japanese Patent Application Laid-Open No. 2017-111409, there is a description of a technology including setting the average area of the crystal grains of an Al alloy having specific composition to from 3 to 100 μm2.
According to an investigation made by the inventors of the present invention, in each of the electrophotographic photosensitive members described in International Publication No. WO2019/077705, Japanese Patent Application Laid-Open No. 2009-150958, and Japanese Patent Application Laid-Open No. 2017-111409, when image formation is repeatedly performed under a high-temperature and high-humidity environment, a defect has occurred in an output image in some cases.
Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member, which is suppressed from causing a defect in an output image when image formation is repeatedly performed under a high-temperature and high-humidity environment.
The object is achieved by the present invention described below. That is, an electrophotographic photosensitive member according to one aspect of the present invention is an electrophotographic photosensitive member comprising: a support having a cylindrical shape; and a photosensitive layer, wherein the support has a surface formed of Al and/or an Al alloy, wherein the surface of the support comprises Al crystal grains having: (α) a plane at −15° or more and less than +15° with respect to a {001} orientation; (β) a plane at −15° or more and less than +15° with respect to a {101} orientation; and (γ) a plane at −15° or more and less than +15° with respect to a {111} orientation, wherein a ratio of an area occupied by the Al crystal grain having the (β) to a total area of the surface of the support is 10% or less, and wherein a ratio of an area occupied by the Al crystal grain having the (γ) to the total area of the surface of the support is more than 10%.
A process cartridge according to another aspect of the present invention is a process cartridge comprising: the above-mentioned electrophotographic photosensitive member; and at least one unit selected from the group consisting of: a charging unit; a developing unit; and a cleaning unit, the process cartridge integrally supporting the electrophotographic photosensitive member and the at least one unit, and being removably mounted onto a main body of an electrophotographic apparatus.
An electrophotographic apparatus according to still another aspect of the present invention comprises: the above-mentioned electrophotographic photosensitive member; a charging unit; an exposing unit; a developing unit; and a transferring unit.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The present invention is described in detail below by way of an exemplary embodiment.
The inventors of the present invention have made an investigation, and as a result, have found that in each of the technologies described in International Publication No. WO2019/077705, Japanese Patent Application Laid-Open No. 2009-150958, and Japanese Patent Application Laid-Open No. 2017-111409, when image formation is repeatedly performed under a high-temperature and high-humidity environment, the support of the electrophotographic photosensitive member may be corroded by the characteristics of the crystal of the Al or Al alloy of the support, and the corrosion causes a defect in an output image.
To solve the above-mentioned technical problem that has occurred in the related art, the inventors of the present invention have made an investigation on the crystal orientations of the surface of an aluminum-made support.
As a result of the above-mentioned investigation, the inventors have found that the use of the following electrophotographic photosensitive member according to the present invention can solve the above-mentioned technical problem.
That is, an electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member comprising: a support having a cylindrical shape; and a photosensitive layer, wherein the support has a surface formed of Al and/or an Al alloy, wherein the surface of the support comprises Al crystal grains having: (α) a plane at −15° or more and less than +15° with respect to a {001} orientation; (β) a plane at −15° or more and less than +15° with respect to a {101} orientation; and (γ) a plane at −15° or more and less than +15° with respect to a {111} orientation, wherein a ratio of an area occupied by the Al crystal grain having the (β) to a total area of the surface of the support is 10% or less, and wherein a ratio of an area occupied by the Al crystal grain having the (γ) to the total area of the surface of the support is more than 10%.
In the present invention, for example, the term “plane at −15° or more and less than +15° with respect to a {111} orientation” refers to a crystal plane having a plane variation of −15° or more and less than +15° with respect to the {111} orientation in an aluminum crystal.
The inventors of the present invention have conceived the mechanism via which the configuration of the present invention can solve the above-mentioned technical problem in the related art to be as described below.
Aluminum has the following three crystal orientations according to a broad classification: a {101} orientation, a {001} orientation, and a {111} orientation. As described in “Kobelnics ([No. 28], Vol. 14, 2005. OCT)”, in general, for example, as illustrated in
The inventors of the present invention have assumed that the ease with which the crystal grains corrode varies depending on their crystal orientations. Specifically, the inventors of the present invention have assumed that the crystal grains each having (γ) a plane at −15° or more and less than +15° with respect to the {111} orientation, and the crystal grains each having (α) a plane at −15° or more and less than +15° with respect to the {001} orientation corrode less easily than the crystal grains each having (β) a plane at −15° or more and less than +15° with respect to the {101} orientation do.
It is conceived that in an aluminum-made support in the related art, crystal grains having the three kinds of crystal orientations are present at random, and hence the support has tended to be liable to corrode owing to the crystal grains each having the (β).
A support for an electrophotographic photosensitive member whose surface is formed of Al and/or an Al alloy typically has satisfactory corrosion resistance because the support has an oxide film on the surface. However, when the oxide film is not sufficient for some reason, corrosion may locally occur on the surface of the support to be responsible for an image defect that is so-called a spot.
In view of the foregoing, in the present invention, the surface of the aluminum-made support is formed under a state in which the ratio of the crystal grains each having the (β), which are assumed to be liable to corrode, is reduced, and the ratio of the crystal grains each having the (γ), which are assumed to hardly corrode, is increased as illustrated in, for example, each of
The inventors have conceived the reason why the ease with which the crystal grains corrode varies depending on their crystal orientations to be as described below.
The surface free energy of an aluminum crystal varies depending on its orientation. The crystal grains of the crystal are arranged in order of decreasing surface free energy as follows: crystal grains each having (β)>crystal grains each having (α)>crystal grains each having (γ). The inventors have conceived that the ease of corrosion is changed by the difference in surface free energy. Accordingly, it can be expected from the magnitude of the surface free energy that the crystal grains each having the (β) are least corrosion-resistant, and the crystal grains each having the (γ) are most corrosion-resistant.
The inventors of the present invention have found from such idea that the above-mentioned technical problem can be solved as described below. That is, in the surface of the aluminum-made support, the ratio of the crystal grains each having the (β), which have large surface free energy, and are hence least corrosion-resistant, is reduced, and the ratio of the crystal grains each having the (γ), which have small surface free energy, and are hence most corrosion-resistant, is increased.
The configuration of the electrophotographic photosensitive member according to the present invention is more specifically described below.
The electrophotographic photosensitive member according to the present invention includes a support having a cylindrical shape and a photosensitive layer.
An example of a method of producing the electrophotographic photosensitive member according to the present invention is a method including: preparing coating liquids for respective layers to be described later; applying the liquids in a desired layer order; and drying the liquids. In this case, examples of a method of applying each of the coating liquids include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Of those, dip coating is preferred from the viewpoints of efficiency and productivity.
The support and the respective layers are described below.
The electrophotographic photosensitive member according to the present invention includes a support having a cylindrical shape, and the surface of the support is formed of at least any one selected from Al and an Al alloy. In addition, the surface of the support may be subjected to, for example, hot water treatment, blast treatment, or cutting treatment.
An expression of an Al crystal orientation in the surface direction of the surface of the support in the present invention, for example, a plane of the {001} orientation represents an Al crystal plane with Miller indices. That is, the plane of the {001} orientation is the comprehensive expression of Miller indices representing any one of crystal lattice planes (001), (010), (100), (00−1), (0−10), and (−100).
In the present invention, the surface of the support includes Al crystal grains having: (α) a plane at −15° or more and less than +15° with respect to a {001} orientation; (β) a plane at −15° or more and less than +15° with respect to a {101} orientation; and (γ) a plane at −15° or more and less than +15° with respect to a {111} orientation.
In addition, a ratio of an area occupied by Al crystal grains each having the (β) to a total area of the surface of the support is 10% or less, and a ratio of an area occupied by Al crystal grains each having the (γ) to the total area of the surface of the support is more than 10%.
From the viewpoint of improving the corrosion resistance of the support, the ratio of the area occupied by the Al crystal grains each having the (γ) to the total area of the surface of the support is preferably 11% or more, more preferably 50% or more, still more preferably 75% or more.
In addition, from the viewpoint of reducing a plane that is liable to corrode, the ratio of the area occupied by the Al crystal grains each having the (β) to the total area of the surface of the support is preferably 5% or less.
In the present invention, the crystal orientations of the Al crystal grains of the surface of the support may be measured, for example, as described below.
First, the surface of the support is treated, for example, by buffing and with an aqueous solution of sodium hydroxide, and the measurement of the crystal orientations of the Al crystal grains is performed for points within 20 μm from the surface of the support before the treatment. The measurement of the crystal orientations is preferably performed by an SEM-EBSP method.
A Field Emission-Scanning Electron Microscope (FE-SEM) including an Electron Back Scatter diffraction Pattern (EBSP) detector is used for the measurement by the SEM-EBSP method. Herein, the “SEM-EBSP method” refers to a method that enables the crystal orientations at the electron beam incidence position to be determined by analyzing a Kikuchi pattern obtained from backscattered electrons occurring when an electron beam is allowed to enter the surface of a test piece. In addition, the “Kikuchi pattern” refers to a pattern that appears behind an electron diffraction image in a pair of white and black parallel lines, in a band shape, or in an array shape at the time of scattering and diffraction of electron beams hit on a crystal.
For example, a field emission scanning electron microscope (product name: JSM-6500F, manufactured by JEOL Ltd.) may be used as the FE-SEM including the EB SP detector.
In the present invention, the surface of the support includes Al crystal grains having: (α) a plane at −15° or more and less than +15° with respect to a {001} orientation; (β) a plane at −15° or more and less than +15° with respect to a {101} orientation; and (γ) a plane at −15° or more and less than +15° with respect to a {111} orientation. In addition, a ratio of an area occupied by Al crystal grains each having the (β) to a total area of the surface of the support is 10% or less, and a ratio of an area occupied by Al crystal grains each having the (γ) to the total area of the surface of the support is more than 10%.
The ratio of the area occupied by the Al crystal grains having each of the above-mentioned crystal orientations may be determined as described below.
As illustrated in
Software attached to the SEM may be used in the calculation of the areas occupied by the Al crystal grains having the respective crystal orientations. In addition, the calculation may be performed, for example, as described below. First, with respect to the crystal orientations obtained through the measurement, the hue “h” of an HSV color space is used to determine the range of (α) to be 0≤h<60 and 300≤h<360, the range of ((3) to be 60≤h<180, and the range of (γ) to be 180≤h<300. Subsequently, hue mapping of the regions of the Al crystal grains having the respective crystal orientations is performed.
The Al alloy for forming the surface of the support preferably contains 0.2 to 0.6 mass % of Si and 0.45 to 0.9 mass % of Mg from the viewpoint of controlling the crystal orientations. A 6000 series Al alloy such as a JIS A6063 alloy is preferably used as such Al alloy. The JIS A6063 alloy is specifically an Al alloy containing 0.2 to 0.6 mass % of Si, 0.35 mass % or less of Fe, 0.1 mass % or less of Cu, 0.1 mass % or less of Mn, 0.45 to 0.9 mass % of Mg, 0.1 mass % or less of Cr, 0.1 mass % or less of Zn, and 0.1 mass % or less of Ti.
The Al alloy for forming the surface of the support may be an Al alloy containing 0.05 to 0.2 mass % of Cu and 1.0 to 1.5 mass % of Mn from the viewpoint of controlling the crystal orientations. Such Al alloy is, for example, a 3000 series Al alloy such as a JIS A3003 alloy. The JIS A3003 alloy is specifically an Al alloy containing 0.6 mass % or less of Si, 0.7 mass% or less of Fe, 0.05 to 0.2 mass % of Cu, 1.0 to 1.5 mass % of Mn, and 0.1 mass % or less of Zn.
A method of producing the support is not particularly limited as long as the method enables the production of a support that satisfies the requirement of the present invention.
An example of the method of producing the support is a method including the following four steps.
When the crystal orientations are controlled through annealing, the crystal orientations can be controlled by adjusting a temperature increase time, an annealing temperature, a maintenance time, and a cooling rate.
In particular, when the annealing temperature is set to from 405 to 450° C., and a cooling rate is set to 8° C./min or more, in the surface of the support, the ratio of the area occupied by the crystal grains each having the (β) reduces, and the ratio of the area occupied by the crystal grains each having the (γ) increases.
Further, the ratios of the respective crystal grains may be controlled by a temperature increase rate and the maintenance time, and it is preferred that the temperature increase rate be set to 10° C./min or less, and the maintenance time be set to 2.5 hours or less.
In addition, a thermal history is important at the time of the control of the crystal orientations, and hence the Al alloy that has undergone the first step of performing hot extrusion processing and the second step of performing cold drawing described above is preferably annealed before use.
In the present invention, an electroconductive layer may be arranged on the support. The arrangement of the electroconductive layer can conceal flaws and irregularities in the surface of the support, and control the reflection of light on the surface of the support.
The electroconductive layer preferably contains electroconductive particles and a resin.
A material for the electroconductive particles is, for example, a metal oxide, a metal, or carbon black.
Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of the metal include aluminum, nickel, iron, nichrome, copper, zinc, and silver.
Of those, a metal oxide is preferably used as the electroconductive particles, and in particular, titanium oxide, tin oxide, and zinc oxide are more preferably used.
When the metal oxide is used as the electroconductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element, such as phosphorus or aluminum, or an oxide thereof
In addition, each of the electroconductive particles may be of a laminated construction having a core particle and a coating layer coating the particle. Examples of the core particle include titanium oxide, barium sulfate, and zinc oxide. The coating layer is, for example, a metal oxide such as tin oxide.
In addition, when the metal oxide is used as the electroconductive particles, their volume-average particle diameter is preferably from 1 to 500 nm, more preferably from 3 to 400 nm.
Examples of the resin include a polyester resin, a polycarbonate resin, a polyvinyl acetal resin, an acrylic resin, a silicone resin, an epoxy resin, a melamine resin, a polyurethane resin, a phenol resin, and an alkyd resin.
In addition, the electroconductive layer may further contain a concealing agent, such as a silicone oil, resin particles, or titanium oxide.
The electroconductive layer has a thickness of preferably from 1 to 50 μm, particularly preferably from 3 to 40 μm.
The electroconductive layer may be formed by preparing a coating liquid for an electroconductive layer containing the above-mentioned materials and a solvent, forming a coat thereof, and drying the coat. Examples of the solvent to be used for the coating liquid include an alcohol-based solvent, a sulfoxide-based solvent, a ketone-based solvent, an ether-based solvent, an ester-based solvent, and an aromatic hydrocarbon-based solvent. As a dispersion method for dispersing the electroconductive particles in the coating liquid for an electroconductive layer, there are given methods including using a paint shaker, a sand mill, a ball mill, and a liquid collision-type high-speed disperser.
In the present invention, an undercoat layer may be arranged on the support or the electroconductive layer. The arrangement of the undercoat layer can improve an adhesive function between layers to impart a charge injection-inhibiting function.
The undercoat layer preferably contains a resin. In addition, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.
Examples of the resin include a polyester resin, a polycarbonate resin, a polyvinyl acetal resin, an acrylic resin, an epoxy resin, a melamine resin, a polyurethane resin, a phenol resin, a polyvinyl phenol resin, an alkyd resin, a polyvinyl alcohol resin, a polyethylene oxide resin, a polypropylene oxide resin, a polyamide resin, a polyamic acid resin, a polyimide resin, a polyamide imide resin, and a cellulose resin.
Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic acid anhydride group, and a carbon-carbon double bond group.
In addition, the undercoat layer may further contain an electron-transporting substance, a metal oxide, a metal, an electroconductive polymer, and the like for the purpose of improving electric characteristics. Of those, an electron-transporting substance and a metal oxide are preferably used.
Examples of the electron-transporting substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, a halogenated aryl compound, a silole compound, and a boron-containing compound. An electron-transporting substance having a polymerizable functional group may be used as the electron-transporting substance and copolymerized with the above-mentioned monomer having a polymerizable functional group to form the undercoat layer as a cured film.
Examples of the metal oxide include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of the metal include gold, silver, and aluminum.
In addition, the undercoat layer may further contain an additive.
The undercoat layer has a thickness of preferably from 0.1 to 50 more preferably from 0.2 to 40 μm, particularly preferably from 0.3 to 30 μm.
The undercoat layer may be formed by preparing a coating liquid for an undercoat layer containing the above-mentioned materials and a solvent, forming a coat thereof, and drying and/or curing the coat. Examples of the solvent to be used for the coating liquid include an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, an ester-based solvent, and an aromatic hydrocarbon-based solvent.
The photosensitive layer of the electrophotographic photosensitive member is mainly classified into (1) a laminate-type photosensitive layer and (2) a monolayer-type photosensitive layer. (1) The laminate-type photosensitive layer has a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance. (2) The monolayer-type photosensitive layer has a photosensitive layer containing both a charge-generating substance and a charge-transporting substance.
The laminate-type photosensitive layer includes the charge-generating layer and the charge-transporting layer.
The charge-generating layer preferably contains the charge-generating substance and a resin.
Examples of the charge-generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Of those, azo pigments and phthalocyanine pigments are preferred. Of the phthalocyanine pigments, an oxytitanium phthalocyanine pigment, a chlorogallium phthalocyanine pigment, and a hydroxygallium phthalocyanine pigment are preferred.
The content of the charge-generating substance in the charge-generating layer is preferably from 40 to 85 mass%, more preferably from 60 to 80 mass % with respect to the total mass of the charge-generating layer.
Examples of the resin include a polyester resin, a polycarbonate resin, a polyvinyl acetal resin, a polyvinyl butyral resin, an acrylic resin, a silicone resin, an epoxy resin, a melamine resin, a polyurethane resin, a phenol resin, a polyvinyl alcohol resin, a cellulose resin, a polystyrene resin, a polyvinyl acetate resin, and a polyvinyl chloride resin. Of those, a polyvinyl butyral resin is more preferred.
In addition, the charge-generating layer may further contain an additive, such as an antioxidant or a UV absorber. Specific examples thereof include a hindered phenol compound, a hindered amine compound, a sulfur compound, a phosphorus compound, and a benzophenone compound.
The charge-generating layer has a thickness of preferably from 0.1 to 1 μm, more preferably from 0.15 to 0.4 μm.
The charge-generating layer may be formed by preparing a coating liquid for a charge-generating layer containing the above-mentioned materials and a solvent, forming a coat thereof, and drying the coat. Examples of the solvent to be used for the coating liquid include an alcohol-based solvent, a sulfoxide-based solvent, a ketone-based solvent, an ether-based solvent, an ester-based solvent, and an aromatic hydrocarbon-based solvent.
The charge-transporting layer preferably contains the charge-transporting substance and a resin.
Examples of the charge-transporting substance include a polycyclic aromatic compound, a heterocyclic compound, a hydrazone compound, a styryl compound, an enamine compound, a benzidine compound, a triarylamine compound, and a resin having a group derived from each of these substances. Of those, a triarylamine compound and a benzidine compound are preferred.
The content of the charge-transporting substance in the charge-transporting layer is preferably from 25 to 70 mass %, more preferably from 30 to 55 mass % with respect to the total mass of the charge-transporting layer.
Examples of the resin include a polyester resin, a polycarbonate resin, an acrylic resin, and a polystyrene resin. Of those, a polycarbonate resin and a polyester resin are preferred. A polyarylate resin is particularly preferred as the polyester resin.
A content ratio (mass ratio) between the charge-transporting substance and the resin is preferably from 4:10 to 20:10, more preferably from 5:10 to 12:10.
In addition, the charge-transporting layer may contain an additive, such as an antioxidant, a UV absorber, a plasticizer, a leveling agent, a slipperiness-imparting agent, or a wear resistance-improving agent. Specific examples thereof include a hindered phenol compound, a hindered amine compound, a sulfur compound, a phosphorus compound, a benzophenone compound, a siloxane-modified resin, a silicone oil, fluorine resin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.
The charge-transporting layer has a thickness of from 5 to 50 μm, more preferably from 8 to 40 μm, particularly preferably from 10 to 30 μm.
The charge-transporting layer may be formed by preparing a coating liquid for a charge-transporting layer containing the above-mentioned materials and a solvent, forming a coat thereof, and drying the coat. Examples of the solvent to be used for the coating liquid include an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, an ester-based solvent, and an aromatic hydrocarbon-based solvent. Of those solvents, an ether-based solvent or an aromatic hydrocarbon-based solvent is preferred.
The monolayer-type photosensitive layer may be formed by preparing a coating liquid for a photosensitive layer containing the charge-generating substance, the charge-transporting substance, a resin, and a solvent, forming a coat thereof, and drying the coat. Examples of the charge-generating substance, the charge-transporting substance, and the resin are the same as those listed as the materials in the section “(1) Laminate-type Photosensitive Layer.”
In the present invention, a protective layer may be arranged on the photosensitive layer. The arrangement of the protective layer can improve durability.
The protective layer preferably contains electroconductive particles and/or a charge-transporting substance, and a resin.
Examples of the electroconductive particles include particles of metal oxides, such as titanium oxide, zinc oxide, tin oxide, and indium oxide.
Examples of the charge-transporting substance include a polycyclic aromatic compound, a heterocyclic compound, a hydrazone compound, a styryl compound, an enamine compound, a benzidine compound, a triarylamine compound, and a resin having a group derived from each of these substances. Of those, a triarylamine compound and a benzidine compound are preferred.
Examples of the resin include a polyester resin, an acrylic resin, a phenoxy resin, a polycarbonate resin, a polystyrene resin, a phenol resin, a melamine resin, and an epoxy resin. Of those, a polycarbonate resin, a polyester resin, and an acrylic resin are preferred.
In addition, the protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. As a reaction in this case, there are given, for example, a thermal polymerization reaction, a photopolymerization reaction, and a radiation polymerization reaction. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an acryloyl group and a methacryloyl group. A material having a charge-transporting ability may be used as the monomer having a polymerizable functional group.
The protective layer may contain an additive, such as an antioxidant, a UV absorber, a plasticizer, a leveling agent, a slipperiness-imparting agent, or a wear resistance-improving agent. Specific examples thereof include a hindered phenol compound, a hindered amine compound, a sulfur compound, a phosphorus compound, a benzophenone compound, a siloxane-modified resin, a silicone oil, fluorine resin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.
The protective layer has a thickness of preferably from 0.5 to 10 μm, more preferably from 1 to 7 μm.
The protective layer may be formed by preparing a coating liquid for a protective layer containing the above-mentioned materials and a solvent, forming a coat thereof, and drying and/or curing the coat. Examples of the solvent to be used for the coating liquid include an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, a sulfoxide-based solvent, an ester-based solvent, and an aromatic hydrocarbon-based solvent.
A process cartridge according to the present invention is characterized in that the process cartridge integrally supports the electrophotographic photosensitive member described above and at least one unit selected from the group consisting of: a charging unit; a developing unit; and a cleaning unit, and is removably mounted onto the main body of an electrophotographic apparatus.
In addition, an electrophotographic apparatus according to the present invention is characterized by including the electrophotographic photosensitive member described above, a charging unit, an exposing unit, a developing unit, and a transferring unit.
An example of the schematic configuration of an electrophotographic apparatus including a process cartridge including an electrophotographic photosensitive member is illustrated in
An electrophotographic photosensitive member 1 having a cylindrical shape is rotationally driven about a shaft 2 in a direction indicated by the arrow at a predetermined peripheral speed. The surface of the electrophotographic photosensitive member 1 is charged to a predetermined positive or negative potential by a charging unit 3.
Although a roller charging system based on a roller-type charging member is illustrated in the figure, a charging system, such as a corona charging system, a contact charging system, or an injection charging system, may be adopted.
The charged surface of the electrophotographic photosensitive member 1 is irradiated with exposure light 4 from an exposing unit (not shown), and hence an electrostatic latent image corresponding to target image information is formed thereon. The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed with a toner stored in a developing unit 5, and a toner image is formed on the surface of the electrophotographic photosensitive member 1. The toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred onto a transfer material 7 by a transferring unit 6. The transfer material 7 onto which the toner image has been transferred is conveyed to a fixing unit 8, is subjected to treatment for fixing the toner image, and is printed out to the outside of the electrophotographic apparatus.
The electrophotographic apparatus may include a cleaning unit 9 for removing a deposit such as the toner remaining on the surface of the electrophotographic photosensitive member 1 after the transfer. In addition, a so-called cleaner-less system in which the deposit is removed with the developing unit 5 or the like without separate arrangement of the cleaning unit 9 may be used.
The electrophotographic apparatus may include an electricity-removing mechanism for subjecting the surface of the electrophotographic photosensitive member 1 to electricity-removing treatment with pre-exposure light 10 from a pre-exposing unit (not shown). In addition, a guiding unit 12 such as a rail may be arranged for removably mounting a process cartridge 11 according to the present invention onto the main body of the electrophotographic apparatus.
The electrophotographic photosensitive member according to the present invention can be used in, for example, a laser beam printer, an LED printer, a copying machine, a facsimile, and a multifunctional peripheral thereof.
According to the present invention, the electrophotographic photosensitive member, which is suppressed from causing a defect in an output image when image formation is repeatedly performed under a high-temperature and high-humidity environment, can be provided.
The present invention is described in more detail below by way of Examples and Comparative Examples. The present invention is by no means limited to the following Examples, and various modifications may be made without departing from the gist of the present invention. In the description in the following Examples, “part(s)” is by mass unless otherwise specified.
A support was produced by the following method.
An extruded tube formed of a JIS A6063 alloy and subjected to hot extrusion molding was subjected to cold drawing processing to provide a drawn tube having an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm.
Next, the drawn tube was loaded into an electric furnace, increased in temperature at a temperature increase rate of 5° C./min, and then maintained at 425° C. for 1 hour. Subsequently, the drawn tube was cooled at 25° C./min until its temperature became 150° C., and was removed from the electric furnace after 24 hours.
The surface of the tube was subjected to mirror cutting after the annealing. Thus, “Support A-1” having an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm was obtained. The production conditions of Support A-1 are shown in Table 1.
The elemental analysis of the drawn tube used showed that the tube was formed of an Al alloy containing 0.4 mass % of Si, 0.3 mass % of Fe, 0.06 mass % of Cu, 0.08 mass % or less of Mn, 0.65 mass % of Mg, 0.05 mass % of Cr, 0.07 mass % of Zn, and 0.06 mass % of Ti.
Supports were each produced in the same manner as in the production example of Support A-1 except that in the production example of Support A-1, the same drawn tube was used, and the annealing conditions were changed as shown in Table 1. The resultant supports are referred to as “Support A-2 to Support A-15.” The production conditions of Supports A-2 to A-15 are shown in Table 1.
An extruded tube formed of a JIS A3003 alloy and subjected to hot extrusion molding was subjected to cold drawing processing to provide a drawn tube having an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm.
Next, the drawn tube was loaded into an electric furnace, increased in temperature at a temperature increase rate of 5° C./min, and then maintained at 405° C. for 1 hour. Subsequently, the drawn tube was cooled at 30° C./min until its temperature became 150° C., and was removed from the electric furnace after 24 hours.
The surface of the tube was subjected to mirror cutting after the annealing. Thus, “Support A-16” having an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm was obtained. The production conditions of Support A-16 are shown in Table 1.
The elemental analysis of the drawn tube used showed that the tube was formed of an Al alloy containing 0.2 mass % of Si, 0.3 mass % of Fe, 0.09 mass % of Cu, 1.3 mass % of Mn, and 0.02 mass % of Zn.
An extruded tube formed of a JIS A6063 alloy and subjected to hot extrusion molding was subjected to cold drawing processing to provide a drawn tube having an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm.
Next, the drawn tube was loaded into an electric furnace, increased in temperature at a temperature increase rate of 5° C./min, and then maintained at 430° C. for 1.5 hours. Subsequently, the drawn tube was cooled at 6° C./min until its temperature became 150° C., and was removed from the electric furnace after 24 hours.
The surface of the resultant was subjected to mirror cutting after the annealing. Thus, “Support B-1” having an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm was obtained. The production conditions of Support B-1 are shown in Table 1.
The elemental analysis of the drawn tube used showed that the tube was formed of an Al alloy containing 0.5 mass % of Si, 0.2 mass % of Fe, 0.07 mass % of Cu, 0.06 mass % or less of Mn, 0.7 mass % of Mg, 0.04 mass % of Cr, 0.06 mass % or less of Zn, and 0.07 mass % of Ti.
Supports were each produced in the same manner as in the production example of Support B-1 except that in the production example of Support B-1, the same drawn tube was used, and the annealing conditions were changed as shown in Table 1. The resultant supports are referred to as “Support B-2 to Support B-12.” The production conditions of Support B-2 to Support B-12 are shown in Table 1.
Annealing was performed with a drawn tube formed of an Al—Mg alloy containing magnesium at a ratio of 2.5 mass %, the tube having an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm, under conditions shown in Table 1. After the annealing, the surface of the tube was subjected to mirror cutting. Thus, “Support B-13 and Support B-14” each having an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm were obtained. The production conditions of Support B-13 and Support B-14 are shown in Table 1.
Support A-1 was used as a support.
Next, 100 parts of zinc oxide particles (specific surface area: 19 m2/g, powder resistivity: 3.6×106 Ω·cm) serving as a metal oxide were stirred and mixed with 500 parts of toluene, and 0.8 part of a silane coupling agent was added to the mixture, followed by stirring for 6 hours. The silane coupling agent used is N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (product name: KBM-602, manufactured by Shin-Etsu Chemical Co., Ltd.). After that, toluene was evaporated under reduced pressure, and the residue was dried under heating at 130° C. for 6 hours to provide surface-treated zinc oxide particles.
Next, the following materials were prepared.
Those materials were dissolved in a mixed solution of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. 80.8 Parts of the surface-treated zinc oxide particles and 0.8 part of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to the solution, and the mixture was subjected to dispersion with a sand mill apparatus using glass beads each having a diameter of 0.8 mm under an atmosphere at 23±3° C. for 3 hours.
Next, the following materials were prepared.
Those materials were added to the solution after dispersion, and the mixture was stirred to prepare a coating liquid for an undercoat layer.
The coating liquid for an undercoat layer was applied onto the support by dip coating, and the resultant coat was dried for 40 minutes at 160° C. to form an undercoat layer having a thickness of 18 μm.
Next, the following materials were prepared.
Those materials were loaded into a sand mill using glass beads each having a diameter of 1 mm, and the mixture was subjected to dispersion treatment for 4 hours. After that, 700 parts of ethyl acetate was added to the dispersed product to prepare a coating liquid for a charge-generating layer. The coating liquid for a charge-generating layer was applied onto the undercoat layer by dip coating, and the resultant coat was dried for 15 minutes at 80° C. to form a charge-generating layer having a thickness of 0.17 um.
Next, the following materials were prepared.
Those materials were dissolved in a mixed solvent of 600 parts of mixed xylene and 200 parts of dimethoxymethane to prepare a coating liquid for a charge-transporting layer. The coating liquid for a charge-transporting layer was applied onto the charge-generating layer by dip coating to form a coat, and the resultant coat was dried for 30 minutes at 100° C. to form a charge-transporting layer having a thickness of 18
Next, a mixed solvent of 20 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane (product name: ZEORORA H, manufactured by Zeon Corporation) and 20 parts of 1-propanol was filtered with a polyflon filter (product name: PF-040, manufactured by Advantec Toyo Kaisha, Ltd.).
In addition, the following materials were prepared.
Those materials were added to the mixed solvent. The mixture was filtered with a polyflon filter (product name: PF-020, manufactured by Advantec Toyo Kaisha, Ltd.) to prepare a coating liquid for a second charge-transporting layer (protective layer). The coating liquid for a second charge-transporting layer was applied onto the charge-transporting layer by dip coating, and the resultant coat was dried in the atmosphere for 6 minutes at 50° C. After that, in nitrogen, the coat was irradiated with electron beams for 1.6 seconds under the conditions of an acceleration voltage of 70 kV and an absorbed dose of 8,000 Gy while the support (irradiation target body) was rotated at 200 rpm. Subsequently, the coat was heated by increasing its temperature from 25° C. to 125° C. in nitrogen over 30 seconds. The oxygen concentrations of the atmosphere at the time of the electron beam irradiation and at the time of the heating after the irradiation were each 15 ppm. Next, the coat was subjected to heating treatment in the atmosphere for 30 minutes at 100° C. to form a 5-micrometer thick second charge-transporting layer (protective layer) cured by the electron beams.
Next, a linear groove was formed on the surface of the protective layer with a polishing sheet (product name: GC3000, manufactured by Riken Corundum Co., Ltd.). The feeding speed of the polishing sheet was set to 40 mm/min, the number of revolutions of the product to be processed was set to 240 rpm, and the pressing pressure of the polishing sheet against the product to be processed was set to 7.5 N/m2. The feeding direction of the polishing sheet and the rotation direction of the product to be processed were set to be the same direction. In addition, a backup roller having an outer diameter of 40 cm and an Asker C hardness of 40 was used. The linear groove was formed in the peripheral surface of the product to be processed under the foregoing conditions over 10 seconds.
Thus, Photosensitive Member A-1 was produced.
Electrophotographic photosensitive members were each produced in exactly the same manner as in Photosensitive Member A-1 except that a support shown in Table 2 was used. The resultant electrophotographic photosensitive members are referred to as “Photosensitive Member A-2 to Photosensitive Member A-16, and Photosensitive Member B-1 to Photosensitive Member B-14.”
A corrosion evaluation was performed by using each of the supports.
First, the support was stored under an environment at 55° C. and 95% RH for 14 days, and then the presence or absence of a corrosion was visually observed. The size of the corrosion that had been visually observed was measured with a measuring microscope (product name: STM-6, manufactured by Olympus Corporation). The maximum length of a corroded site was adopted as the size of the corrosion.
An evaluation rank was determined according to the sizes and number of the corrosions, and in accordance with criteria shown in Table 3. The results are shown in Table 5.
An image evaluation was performed by using each of the electrophotographic photosensitive members produced in Examples and Comparative Examples.
First, the electrophotographic photosensitive member was mounted on the cyan station of an electrophotographic apparatus (copying machine) (product name: imagePRESS C910, manufactured by Canon Inc.) serving as an evaluation apparatus, and automatic gradation correction was performed. After that, the image evaluation was performed as described below. The image evaluation was performed under an environment at 23° C. and 50% RH.
A solid white image and a solid black image were output using A4 size paper GFC-081 (81.0 g/m2, Canon Marketing Japan Inc.), and the numbers of image defects, that is, black spots and white spots, in an area corresponding to one circumference of the electrophotographic photosensitive member in the output images were visually evaluated. The sizes of the black spots and the white spots that had been visually observed were measured with a measuring microscope (product name: STM-6, manufactured by Olympus Corporation). The maximum lengths of the respective spots were adopted as the sizes of the black spots and the white spots. The number of black spots and white spots each having a diameter of 0.1 mm or more was evaluated. The “area corresponding to one circumference of the electrophotographic photosensitive member” is a rectangular region having a length of 297 mm, which is the long-side length of A4 paper, and a width of 96.1 mm, which corresponds to one circumference of the electrophotographic photosensitive member. The resultant spots are defined as initial black spots and white spots.
Next, the electrophotographic photosensitive member that had been evaluated for its initial black spots and white spots was stored under an environment at 55° C. and 95% RH for 14 days, and the same image evaluation as that described above was performed. The resultant spots are defined as black spots and white spots after severe storage.
Finally, a fluctuation was calculated by subtracting the number of the initial black spots and white spots from the number of the black spots and white spots after the severe storage. The calculated value is defined as black spots and white spots serving as a fluctuation.
An evaluation rank was determined according to the sizes and number of the black spots and white spots serving as a fluctuation, the spots each having a diameter of 0.1 mm or more, and in accordance with criteria shown in Table 4. The results are shown in Table 5. The number of spots shown in each of Tables 4 and 5 is the total of the number of the black spots and the number of the white spots.
A crystal orientation evaluation was performed by using each of the electrophotographic photosensitive members produced in Examples and Comparative Examples as described below.
First, positions corresponding to ⅛, 2/8, ⅜, 4/8, ⅝, 6/8, and ⅞ of the full length of the support from one of the ends thereof in the axial direction thereof are determined. Further, at each of the positions, the support is divided into four parts of 90° each in the circumferential direction thereof. At each of the 28 points where the dividing lines in the axial direction and the dividing lines in the circumferential direction intersect, a 10-millimeter square fragment is cut out so that the point of intersection between the dividing line in the axial direction and the dividing line in the circumferential direction is at its center. The protective layer was removed with a polishing sheet, followed by the removal of the photosensitive layer with methyl ethyl ketone. After that, the surface of the support was exposed and subjected to mirror finishing by buffing. Next, the resultant was treated by being immersed in an aqueous solution of sodium hydroxide for 1 minute to provide a sample for crystal orientation observation.
Observation by the SEM-EBSP method was performed for a 100-micrometer square region set so that the center on the surface of the resultant sample, that is, the above-mentioned point of intersection between the dividing line in the axial direction of the support and the dividing line in the circumferential direction thereof was at its center. From the observation results, the ratio of the area occupied by Al crystal grains having each crystal orientation and the average area of the Al crystal grains were calculated. The results are shown in Table 5.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2022-075291, filed Apr. 28, 2022, and Japanese Patent Application No. 2023-052154, filed Mar. 28, 2023, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-075291 | Apr 2022 | JP | national |
| 2023-052154 | Mar 2023 | JP | national |
